With the advent of CNC machines sheet metal aircraft (and to some extent , steel tube structures) have become vastly easier to put together. While the theory is simple enough, I have always wondered just exactly how it is done.
Using pre-punched skins as templates and then drilling through them into the underlying ribs or bulkheads is one method to speed things up and ensure a more accurate structure.
But when it comes to complete matched hole tooling, where you can take your wing skins and wrap them around the ribs and the holes all line up - this has to be a very clever process. The later RV's supposedly use this method. The Savannah kits allegedly even have all the holes punched to the right size and de-burred for riveting - no drilling is even required.
Does this technique require complete 3D modeling of the structures and the computer then takes into account curvature and thicknesses before creating the cutting/punching files for the CNC machines?
For example, when taking a wing rib blank and punching the holes in the flanges to which the skins later attach, how on earth can those holes be guaranteed to line up with the wing skin holes after the flange is bent ?
Anybody out there worked on this kind of stuff who can give me some insight?
Using pre-punched skins as templates and then drilling through them into the underlying ribs or bulkheads is one method to speed things up and ensure a more accurate structure.
But when it comes to complete matched hole tooling, where you can take your wing skins and wrap them around the ribs and the holes all line up - this has to be a very clever process. The later RV's supposedly use this method. The Savannah kits allegedly even have all the holes punched to the right size and de-burred for riveting - no drilling is even required.
Does this technique require complete 3D modeling of the structures and the computer then takes into account curvature and thicknesses before creating the cutting/punching files for the CNC machines?
For example, when taking a wing rib blank and punching the holes in the flanges to which the skins later attach, how on earth can those holes be guaranteed to line up with the wing skin holes after the flange is bent ?
Anybody out there worked on this kind of stuff who can give me some insight?
